From mboxrd@z Thu Jan 1 00:00:00 1970 From: ddegraff Subject: Re: Need help to measure and tune the latency in Linux RT Date: Tue, 30 Apr 2013 07:02:16 -0500 Message-ID: <517FB2C8.10705@neb.rr.com> References: Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-newbie-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Ashoka K Cc: linux-embedded@vger.kernel.org, linux-newbie@vger.kernel.org On 04/30/2013 03:27 AM, Ashoka K wrote: > Hi, > > I have an embedded system running 2.6.33 cross compiled for ARM OMAP > with 1 GHZ uni-processor system. A project I am working on is using the same vintage kernel with RT patches applied, though on DaVinci (omap l138). I, myself, however, have not dealt with any of that work, but I will ask the other developer if he has any suggestions. > > The application has many threads and processes (around 15 total). In > that 1 thread is time critical and must run every interval confiurable > as 2, 4 or 8 milli sec etc. There is another thread which transfers > Images to a FTP or to HMI etc, whoever requested the image. > With this image transfer enabled my critical process misses the > deadline and timesout. This critical thread is at RR priority 50. I > used a HR timer thread with RR pri 55 to wakeup the critical thread > every 1 milli sec to do the job. > If image transfer is enabled i see that real time thread misses deadlines. > > All traffic is flowing on common ethernet connection. Does it affect > in any way ? > > How to find out where the kernel is waiting or delaying to schedule > the critical thread even though it is at higher RR priority. How to > measure the latency ? > > I am trying to use Oprofile tool, but got some error in cross > compiling. Doesn't these tools add their own latency to the original > problem ? > > Any tools ? which one is better. Please provide your input on this. > > > Regards > Ashoka. K > -- > To unsubscribe from this list: send the line "unsubscribe linux-embedded" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs